Smart Module Series
SA800U-WF Hardware Design
SA800U-WF_Hardware_Design 47 / 106
A reference design for battery charging circuit is shown below.
GND
BAT_THERM
VBAT
0.01R
100
μ
F
NTC
VBAT
33 pF
1
μ
F
ESD
USB_VBUS
Adapter or USB
Module
Battery
C1
C2
C3
R1
D1
D2
BAT_P
ESD
BAT_M
GND
CS_M
CS_P
Figure 12: Reference Design for Battery Charging Circuit
SA800U-WF offers a fuel gauge algorithm which
is able to accurately estimate the battery’s health state
by current and voltage monitoring techniques. Using precise measurements of battery voltage, current,
and temperature, the fuel gauge provides a dependable state of charge estimate throughout the entire life
of the battery and across a broad range of operating conditions. It effectively protects the battery from
over-discharging, and also allows you to estimate the battery life based on the battery level to timely save
important data before complete power-down.
Mobile devices such as mobile phone and game machine systems are powered by batteries. When
different batteries are used, the charging and discharging curve has to be modified according to the
battery type to achieve the best performance.
If thermistor is not available in the battery, or an adapter rather than a battery is used to power the module,
BAT_THERM should be connected to GND with a 47 k
Ω resistor. Otherwise the system may be unable to
detect the battery, which will cause power-on failure. BAT_P and BAT_M must be connected, and also
CS_P and CS_M must be connected, otherwise there may be abnormalities in using the module. BAT_P
and BAT_M are used for battery level detection, and they should be routed as a differential pair to ensure
accuracy. CS_P and CS_M are used for charging current sensing, and they should be routed as a
differential pair to ensure accuracy.
